They are two of Hong Kong's best-known tycoons, and among the richest property-dealing magnates in Asia, brothers whose narrative is steeped in a history of mouthwatering investments, a divisive feud, kidnapping, affairs and untold wealth.

To that list must now be added criminal prosecution, as the Kwok brothers have been formally charged over alleged bribes to one of Hong Kong's most senior officials in a case that sent shivers through a political and business elite that is used to conducting its affairs with impunity.

Thomas Kwok Ping-kwong and Raymond Kwok Ping-luen are charged over allegations that the former chief secretary Rafael Hui was bribed for the best part of a decade until 2009. Hui is alleged to have enjoyed the rent-free use of two apartments and two unsecured loans while he was the second most senior government official, worth a total of HK$34m (£2.8m).

Two others linked to the Kwok brothers' huge empire, Sun Hung Kai Properties, have also been charged over the same allegations: the company's executive director, Thomas Chan Kui-yuen, and the businessman Francis Kwan Hung-sang.

The move marks a bold new gambit by Hong Kong's Independent Commission Against Corruption (ICAC), which has taken on one of its biggest challenges since it was formed in the 1970s to sweep corruption out of the police.

"I think this shows Hong Kong in a very good light," said a partner in a leading Hong Kong law firm. "It means that if there is wrongdoing, no one is above the law. I don't think you can say that about the rest of China or indeed about many places in the world."

Walter Kwok Ping-sheung, the elder brother to Thomas and Raymond, is not among those charged. It is understood he was ejected from control of the family firm in 2008. He was kidnapped 15 years ago by the notorious Cheung Tze-keung, alias "Big Spender", and his gang and held in a cage before a ransom was paid. His subsequent relationship with the lawyer Ida Tong is believed to have damaged his ties with his wife and family.

Hong Kong has long prided itself on its rule of law and its firm action against corruption, in contrast to neighbouring mainland China.

That faith had fractured in recent months, however, with the exposure of a series of scandals involving the highest levels of government and business, and a rising anger at the growing gap between rich and poor.

Trading in Sun Hung Kai Properties shares was halted on Friday morning, although the company has in recent weeks continued to buy sites in Hong Kong for development.

Meanwhile, the current administration has been hit by the resignation on Wednesday of Mak Chai-kwong – a minister in the new government who managed just 12 days in his job – over possible abuse of a civil servants' rent perk. He denies any wrongdoing.